1. Field of the Invention
The present invention relates generally to devices for use with internal combustion engines and specifically for vaporizing the conventional liquid-type fuel into a gas vapor prior to use by said engine for increased efficiency and reduced pollutants, and also for preheating the carburetor to assist in operation of the engine.
2. Description of the Prior Art
It has been known in the prior art to vaporize liquid fuel into the gaseous state by the use of heat exchange systems in contact with the hot exhaust manifolds of the engines with which the fuel is used. Also, such systems are known using heat exchange systems associated with the muffler and tail pipe systems of such engines. Other combinations use the engine coolant system for heating the liquid fuel. In U.S. Pat. No. 4,106,455, issued to Vance on Aug. 15, 1978, there is disclosed a vaporizer system for gasoline engines which utilizes a fuel line from the pressurized gas tank and passing through the oil pan reservoir to heat the liquid fuel. The fuel is vaporized and passes through the exhaust manifold to maintain the vapor state until it is fed to the carburetor.
Several prior art systems have been proposed for pre-vaporization of the fuel prior to its entry into the intake manifold of an engine in order to provide for more complete combustion of the fuel. For example, U.S. Pat. No. 3,498,279, issued to Seeley, teaches passing the raw gasoline over a hot surface prior to introduction into the carburetor of a standard internal combustion engine or the cylinder of a diesel engine. The surface is heated either by an electrically operated heater or a gas heated countercurrent exchanger employing the hot gaseous products of combustion. U.S. Pat. No. 3,952,716, issued McCauley, discloses a system in which a fuel/air mixture is oscillated by means of a rotor, subjected to sonic vibration, and then passed through a heated grid or screen to promote vaporization. U.S. Pat. No. 3,973,543, issued to Nakada, discloses a system for promoting vaporization of fuel within the intake manifold of an engine by means of an intensive electric field. In U.S. Pat. No. 4,157,700, issued to Conner on June 12, 1979, there is disclosed a pre-vaporization system which utilizes microwaves from a magnetron data transfer medium surrounding a tubular coil in which the liquid gas is vaporized.
The ideal carburetor would pass a mixture of completely vaporized fuel and air in the proper proportion to the intake manifold and cylinders. Complete vaporization of the fuel is not achieved in present day carburetors, however, because of the varying composition of the fuel and other limitations. Moreover, no matter how well mixed and vaporized the fuel mixture may be as it leaves the carburetor, its characteristics are changed as it passes through the manifold. Cold surfaces in the manifold will cause some of the vaporized fuel to condense, and changes in direction of flow will through inertia cause some portions of the mixture to settle out.
Many devices have been proposed to aid the carburetor in breaking up and vaporizing the fuel by heating either the carburetor or the intake manifold. Some of these devices have included means for bringing exhaust gases from the exhaust manifold to the carburetor or to the intake manifold, hot water jackets surrounding the carburetor or the intake manifold, electrical heaters in the carburetor, and so forth. None of these devices has been entirely satisfactory, however, because vaporization of all the gasoline is usually still incomplete until the end of the compression stroke in the cylinder. Combustion is therefore incomplete, resulting in lower engine efficiency and higher amounts of exhaust pollutants. Many of these devices are also expensive, difficult to install, ineffective or similarly unsatisfactory.
Some of the prior art devices are employed prior to the fuel entering the carburetor. In U.S. Pat. No. 4,072,138, issued to Hawkins et al. on Feb. 7, 1978, there is disclosed a fuel system which heats the fuel between the carburetor and the fuel pump with heat derived from a counter-flow circulation through the hot water of the engine cooling system. An isothermal fuel supply system is disclosed in U.S. Pat. No. 4,027,639, issued to Amano on June 7, 1977, in which the fuel to the carburetor is preheated by heat exchange with the engine cooling water. Means for superheating the fuel under pressure and then directing it to the carburetor are disclosed in U.S. Pat. No. 4,083,340, issued to Furr et al. on Apr. 11, 1978.
Many of the other prior art devices involve systems in which the fuel or fuel vapor is treated after passage into the carburetor. The carburetor design disclosed in U.S. Pat. No. 4,029,065, issued to Wood on June 14, 1977, uses a finned heat exchanger connected to the engine cooling system and inserted between the carburetor nozzle and intake manifold to help vaporize the fuel. The carburetor disclosed in U.S. Pat. No. 4,089,314, issued to Bernecker on May 16, 1978 includes porous matter within the carburetor to effect vaporization of the fuel. The devices disclosed in U.S. Pat. No. 4,050,430, issued Amagai et al. on Sept. 27, 1977, and U.S. Pat. No. 4,083,343, issued to Paton on Apr. 11, 1978, include means for heating the air utilized by the carburetor for combination with the vaporized fuel.
In U.S. Pat. No. 4,137,875, issued to Medina on Feb. 6, 1979, there is disclosed an auxiliary air inlet device for internal combustion engines which includes a plate mounted between the carburetor and the manifold and having a cavity for admitting air from the atmosphere to the air/fuel mixture. The fuel atomizing unit disclosed in U.S. Pat. No. 4,020,812, issued to Hayward on May 3, 1977, includes several plates providing an aperture aligned between the carburetor and the intake manifold and having spaced apart screens with an electric heating element therebetween. In U.S. Pat. No. 3,892,211, issued to Oyama on July 1, 1975, there is disclosed a fuel/air mixture heating device in which the fuel from the carburetor is heated prior to entrance to the intake manifold. The fuel vaporizing device disclosed in U.S. Pat. No. 4,108,953, issued to Rocco on Aug. 22, 1978, includes a coaxial heating coil and screen through which the fuel is passed. The fuel vaporizing apparatus shown in U.S. Pat. No. 4,068,638, issued to Butler on Jan. 17, 1978, provides several metal balls or other items to have flow surfaces for mixing the fuel/air mixture received from the carburetor. An apparatus for improving fuel vaporization which uses a heat exchange for the fuel/air mixture with the engine exhaust gas or another high temperature fluid is disclosed in U.S. Pat. No. 3,985,112, issued to Jordan on Oct. 12, 1976. In U.S. Pat. No. 4,031,876, issued to Hoots on June 28, 1977, there is disclosed a fuel atomizer which includes screened apertures positioned between the carburetor and manifold.
As a further consideration, in an internal combustion engine the pollutants are constituted by oxides of nitrogen, unburned hydrocarbons and carbon monoxide. However, it is not only the emission from the engine exhaust into the atmosphere which creates an ecological problem, but the emitted substances as well give rise to chemical reactions in the atmosphere when radiant energy is supplied by the sun. Thus, the smog now encountered in many major cities is largely the result of photochemical reactions involving unburned hydrocarbons from automobile exhausts. These unburned hydrocarbons are also responsible for inefficient engine operation, in that carbon deposits are formed on the walls of the combustion chambers. With many existing internal combustion engines, a measurable portion of the fuel supplied thereto remains unburned and is discharged. This not only results in an uneconomical engine operation, but it also contaminates the atmosphere.